1. Field of the Invention
The invention relates to an image forming apparatus, a computer readable storage medium and an image forming method.
2. Description of Related Art
In recent years, image forming apparatuses, such as a printer and an MFP (Multi Function Peripheral), have been widely used. This image forming apparatus receives data (PDL data) having a format of a PDL (Page Description Language), such as a PS (Post Script (registered trademark)) created by an external device such as a PC (Personal Computer) or a PCL (Printer Control Language), through a network such as a LAN, converts the received data into data having an intermediate format (intermediate data), rasterizes the intermediate data to generate bitmap data, and performs a print.
Further, an image forming apparatus has increased, which receives PDF data and XPS data without converting the PDF data and the XPS data into PDL data on a printer driver in an external apparatus and so on, converts the received data into intermediate data, rasterizes the intermediate data to generate bitmap data, and performs a print. This process is called a PDF direct print and an XPS direct print.
Print data, such as the PDF data or the XPS data, has a transparency function that transparently overlaps a plurality of image data and displays one image.
Meanwhile, when the image forming apparatus executes a transparency process (process using a transparency function), the image forming apparatus needs a large amount of memories, but the amount of memories that can be mounted in the image forming apparatus is limited. Therefore, various researches to effectively use the limited amount of memories have been performed.
For example, Japanese Laid-Open Patent Publication (JP-A) No. 2005-182692 discloses the following technology. When receiving a drawing command that includes a transparency process, an image forming apparatus automatically determines whether the drawing command allows drawing to be performed even if the transparency process is not executed. When it is determined that the drawing command allows drawing to be performed when the transparency process is not executed, the image forming apparatus changes the drawing command into a drawing command that does not include a transparency process.
However, according to the technology that is disclosed in JP-A No. 2005-182692, since the image forming apparatus automatically determines contents of the transparency process, there are cases where users cannot obtain their desired process results (print result) at all.
Further, as described above, during the transparency process, the image forming apparatus needs a large amount of memories. Therefore, when the amount of memories is insufficient, the transparency process may be changed into a low-speed process using an HDD (Hard Disk Drive), or the transparency process cannot be executed and a print error may be generated.